1. Field of the Invention
The present invention relates to an image forming apparatus for forming a toner image on a sheet material and in particular to an image forming apparatus jointly comprising a mechanism for supplying toner and a memory for recognizing and storing the residual toner in the same mechanism.
2. Related Background Art
Conventionally, this type of image forming apparatus is provided on its toner cartridge and jointly comprises a non-volatile readable/ writable memory for retaining an information item about the residual toner quantity and a circuit substrate for reading/writing an information item from/into this non-volatile memory. The toner cartridge memory and the circuit substrate are provided apart from each other and the exchange of information between them is carried out without contact via a communicating antenna (antenna part).
FIG. 7 is a schematically sectional view showing one example of non-volatile readable/writable memory (toner cartridge) provided on such an image forming apparatus.
Reference Numeral 1 denotes a main frame (main body of image forming apparatus). Reference Numeral 2 denotes a scanner unit. Reference Numeral 3 denotes a toner cartridge and Reference Numeral 4 denotes a toner cartridge memory part. The toner cartridge memory part 4 is arranged at the front end of the toner cartridge 3 and comprises a read/write circuit substrate 5, an antenna part 6, a convey guide unit 7 and a cable 8 for linking a read/write circuit substrate 5 with an antenna part 6. The read/write circuit substrate 5 performs communication with an engine controller (not shown) of the main apparatus body 1. To perform the read/write of an information item to the toner cartridge memory part 4, this read/write circuit substrate 5 also makes a high-frequency current flow into the antenna part 6 not in contact with the same toner cartridge memory part 4 and generates a magnetic field (the magnetic-field generating region is as illustrated). This magnetic field is used to accomplish communication between the antenna part 6 (main apparatus body side) and the toner cartridge memory part 4 (toner cartridge memory side) and read/write a memory information item. The electric control for generating this manetic field is accomplished by means of the read/write circuit substrate 5. The high-frequency current used here is generated by an oscillator element in the read/write circuit substrate and its frequency is set to the order of several tens of MHz. As a result of this, radiant noises are generated from this read/write circuit substrate 5.
In having a toner cartridge memory part 4 provided for detecting an toner cartridge information item like this, a countermeasure against radiant noises generated from the read/write circuit substrate 5 must be taken. For example, it is considered to shield the read/write circuit substrate 5 from the outside.
If the read/write circuit substrate 5 is shielded from the outside, however, a shield member is newly installed, thereby entailing an increase in the manufacturing cost of the relevant image forming apparatus.
The present invention is achieved in consideration of the above problem and its object is to provide an image forming apparatus capable of shielding the radiant noise generated from a communication part by using a simple construction.
It is another object of the present invention to provide an image forming apparatus including: a unit detachably mountable on a main assembly, the unit having at least an image bearing member and a memory; image writing means for writing an image on the image bearing member in accordance with an image information; and communication means for communicating with the memory, in which the communication means is arranged under the above image writing means; and the image writing means functions to shield the radiant noise emitted from the above communication means.